A Scalable Metamaterial with Local Resonance for Low-Frequency Sound Absorption and Its Potential for Nano-Acoustic Applications

The control of low-frequency noise, such as that generated by substations, remains a significant challenge due to the limitations of conventional porous absorbers. This study presents a compact, tunable sound absorption structure based on the local resonance principle of acoustic metamaterials. By optimizing geometric parameters, the resonant frequency is precisely aligned to a target of 100 Hz, achieving a sound absorption coefficient of 0.765. Furthermore, a hierarchical multi-resonator design is implemented, demonstrating high-efficiency absorption (coefficient > 0.8) at key harmonic frequencies up to 500 Hz. While demonstrated here at the macro-scale for industrial noise mitigation, the core design principle, using localized resonances in discrete, tunable units, is inherently scalable. The findings provide a foundational framework for the development of nano-acoustic metamaterials, suggesting potential applications in the management of high-frequency phonons and the design of on-chip nanoelectromechanical systems (NEMS) for integrated optoelectronics, where precise vibrational control is critical.